The main goal of this project is to advance understanding of the possible sex differences in the effects of nicotine withdrawal on negative affect. Current smoking cessation treatments are moderately effective yet even the highest success rates show that over half of smokers relapse back to smoking (Jorenby et al., 1999), and withdrawal symptoms are the most common culprit (Hughes, Higgins, & Hatsukami, 1990). A number of individual differences might account for cessation failures, however some recent studies suggest a discrepancy between men in women in terms of cessation success, with women having a more difficult time remaining abstinent (Pomerleau et al., 2005; Reynosa, Susabda, & Cepeda-Benito, 2005; Westmas & Langsam, 2005). Women also tend to report greater withdrawal distress, reporting particular difficulty with symptoms of negative affect (Ikard & Tomkins, 1973; Livson & Leino, 1988). Indeed, 1 of the most reliable findings in the literature is that withdrawal from cigarettes leads to significant increases in negative affect (Welsch et al., 1999; Piasecki etal., 1997; Baker et al., 2004), and the type of emotions smokers often report during withdrawal are feelings of stress and anxiety (Hughes, 1992; Parrot, 1999). Taken together, this data indicates that important sex differences in smoking behavior and cessation exist and are in need of further study in order to create more effective interventions. The experimental design will allow for comparisons between abstinence groups (24 hour abstinent and non-abstinent) and genders on affective reactivity during a non-stress condition (non-aversive tone), an acute fear condition (shock paired with cue), and an anxiety condition (unpaired shock). Psychophysiological measures of emotional response will be collected and analyzed. The results of this experiment could lead to more specific inferences as to the systems and components of emotional response that are affected by tobacco withdrawal, in addition to elucidating any sex differences in negative affective response during smoking withdrawal. The resulting data may likely advance our understanding of both the basis of sex differences in smoking behavior and cessation success, as well as the treatment of nicotine addiction in general. This increased understanding holds promise to lead to more tailored, and more effective, smoking interventions and better public health outcomes. [unreadable] [unreadable] [unreadable]